Dry cell and lining therefor



June 2, 1931. e. w. HEISE ET AL 7 1,808,410

DRY CELL AND LINING THEREFOR Filed June 11, 1924 Patented June 2, 1931 UNITED STATES PATENT OFFICE GEORGE W. HEISE, OF IBAYSIDE, AND ERWIN A. SCHUMACHER, OF BROOKLYN, NEW YORK, ASSIGNORS TO NATIONAL CARBON COMPANY, INC., A CORPORATION OF NEW YORK DRY CELL AND LINING. THEREFOR Application filed June 11, 1924. Serial No. 719,416.

This invention relates to improvements indry cells of the type comprising a metallic electrode containing a depolarizing mix and a bibulous fabricated sheet between the electrode and mix. A principal object of the invention is to increase the efficiency of such cells by preventing the deterioration of the lining or spacing sheet due to compression or other causes. I

It is well known that dry cells of the nonlining or bag type are generally superior to cells made up with pasted pulpboard, or the like. This superiority is particularly noticeable with respect to shelf life and service on relatively heavy current drain. We have discovered that the inferiority of the paper lined construction is due principally to the partial dehydration of the lining by the compression to which it is subjected when the mix is tamped into the cell.

The dehydration is not caused by absorption of water by the mix, as it is evident even when relatively moist mixes are used. It is not necessarily accompanied by an exudation of paste from the cell, except under particularly high pressure.- The exact nature of the deterimental action is not clear, but it appears to be a consolidation of the lining which makes it unable to transmit and hold liquid in an efficient manner. The resistance of the cell is accordingly increased and the service capacity reduced.

Further, since the compression of the lining is ordinarily not uniform, the corrosion of the zinc is likely to be correspondingly irregular and may be excessive upon limited areas of the container.

These and other difliculties are substantially avoided or minimized by the present in- 40 vention, illustrative embodiments of which are shown in the accompanying drawings.

Fig. 1 is a partial vertical section through a cell having a reinforced lining;

Fig. 2 is a perspective view of a portion of the lining sheet used in the cell of Fig. 1;

Fig. 3 is a plan view of another form of reinforced sheet; and

Fig. 4 is an enlarged sectional view on line IV-IV, Fig. 3.

Referring to Figs. 1 and 2 of the drawings, reference numeral 1 denotes the zinc container electrode of a dry cell having a carbon electrode 2, depolarizing mix 3, and seal 4, all of which may be of the usual type.

The reinforced lining 5, to which the invention primarily relates, is preferably a sheet of ribbed bibulous material. Pulpboard of the quality ordinarily used for cell linings, if suitably stamped to form ribs or similar raised portions on one or both sides of the sheet, will serve our purpose. Better results are obtained, however, by use of ribbed kraft paper. This is a wood pulp board well known on the market. It is ordinarily prepared from long fibre sulfate pulp and is relatively strong and dense as compared with the pulpboard now used in the commercial manufacture of dry cells. We have discovered that kraft paper is adapted to reslst compression in dry cells, but is nevertheless sufliciently porous and absorptive to allow free electrolytic action.

Comparative tests have shown that the improved lining is in general most efficient when its ribs 6 are horizontal and adjacent to the zinc. The invention is not limited to this arrangement, as under some conditions it may be desirable to adopt others. The reinforced lining may be pasted in any suitable way. In the cell illustrated, a layer of paste 7 fills the spaces between the ribs and is substantially uniformly in contact with the zinc.

The ribs may be made by shap ng the pulp board after forming it into sheets, or they may be formed as an incident to the making of the sheets. Instead of being ribbed, the sheets may be stamped to form corrugations. Better results are obtained when the surface of the pulpboard is of the general type shown, but plane surfaced kraft paper or equivalent structure 9 is set. The structure is preferably heavy cords, thin wood, or the like, partly embedded in the sheet and joined at the points of intersection in any suitable manner. The spaces between the cords should be rather large. We do not contemplate using 'a close-meshed structure between the bibulous sheet and the zinc, as objectionable compression may occur if the sheet is rigidly supported over a considerable portion of its surface.

Cells provided with the reinforced lining give service approximating that of non-lining cells. The following results are typical:

0.25 amp. continuous service. Per cent Cell lining duration as com pared with nonhnmg cell Posted pulpboard of ordinary type 64 Corrugated kraft aper (corrugations horizontal,

smooth side to zimg 85 Same, corrugations adjacent zinc 90 As these figures indicate, there is a very striking improvement due to the reinforced lining. So far as we are aware, it had been the uniform belief among dry cell manufacturers that comparative service of 85 or 90% of that given by non-lining cells could not be obtained with a paper-lined cell. A

The commercial importance of the improved construction as described herein is probably most apparent as applied to dry cellsof the six inch 'type. However, this is chiefly due to the fact that the present processes for manufacturing cellsof the flashlight .sizes would require extensive modification to permit the use of a lining of the kind specified. In six-inch cell manufacture this lining may be merely substituted for that now used.

Notwithstanding the inertia of well established processes, opposing radical changes, we regard the reinforced lining for flashlight cells as a potential commercial development. Ordinary paper linings cannot practically be used in these cells. dehydrates such linings to an extent sufficient to raise the internal resistance of the cell to a value precluding the requisite current output for the relatively heavy service required. With the reinforced lining this difliculty is not encountered. The manufacture of the cells isgreatly simplified, since the complicated and expensive procedure of molding The tamping of the mix and wrapping the the mix bobbins, and other steps, is avoided. With a tamped mix, also, 15 to 20% greater weight of mix may be placed in cells of the standard size than .when the wrapped construction is used. Increased service is obtained in this way.

For radio service a rather high internal resistance does not cause the difliculties that it does in flashlight batteries. Such resistance may in fact be advantageous in B batteries or the like subjected to only small current drain. It is therefore not out of the question to use an ordinary pulpboard lining with tamped mix in cells of the miniature or flashlight type designed'for radio service. It is to be noted, however, that a high internal resistance, while not detrimental in itself, is often a symptom of some defect which 'may be very objectionable. As noted above, the compression of the lining is accompanied not only by increase of resistance but also by irre ularity of zinc corrosion andother difliculties. These impair the service of the cells. We therefore prefer to use the reinforced lining of the present invention in radio cells. Shelf.

life is materially improved and an increase of about 10-15% in service life is ordinarilyob- Our invention is broadly a compression resisting bibulous lining for dry cells of the container electrode type and the like. It may be used in combination with other bibulous materials, and in various methods of assem bly. The embodiments ofthe invention illustrated are given by way of example only, and various modifications may be made within the scope of the appended claims.

In our application Serial'No. 719,415, filed of even date herewith, the important advantages of compression-resisting bibulous linings in flat cell constructions are described. The linings of the present invention are also adapted for use in flat cells and the claims are to be construed as applicable to all types of depolarizing mix compressed within said lin- 3. A lining for dry cells comprising one or more layers of kraft paper. 4. A lining for dry cells comprising a linmg of kraft paper, said lining being permeated with an electrolytic solution.

5. In a dry cell the. combination of a posi-- tlve element, a negative element, and a mass of depolarizing mix and a lining of kraft 

